From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E5478CAC58E for ; Thu, 11 Sep 2025 18:02:47 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uwlce-00084K-LN; Thu, 11 Sep 2025 14:02:17 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uwlcT-00083Q-3T for qemu-devel@nongnu.org; Thu, 11 Sep 2025 14:02:08 -0400 Received: from mail-wm1-x336.google.com ([2a00:1450:4864:20::336]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1uwlcN-0003xR-0Z for qemu-devel@nongnu.org; Thu, 11 Sep 2025 14:02:03 -0400 Received: by mail-wm1-x336.google.com with SMTP id 5b1f17b1804b1-45df0cde41bso7844385e9.3 for ; Thu, 11 Sep 2025 11:01:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1757613709; x=1758218509; darn=nongnu.org; h=content-transfer-encoding:in-reply-to:content-language:from :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=dT+Q59Pc2L/rhFNESzM1Obx+v54bS+WG5xyH9LUjUpA=; b=qOoxYgrx6V2wUw0yDrZ/FEn/4WBlMH9CckYDuo6BpGz4cnbLeND2LBbCcW0ZD4PXjk yHW5hbxtGm3l2/5c4l4CCo92h/jK8f+j1my994TUx2f4qouzgiM17yzX/v6vTzO03ih+ qg44Iqy0TGiVse1NpN6MDpYgVEdBLu11tYU1TumzKr2a3XBkiemSn6mMGXsyiIxHpKvB vARcDAQB+TtrVyZP/zpsKLYQajl4L5a3HyG22TDBbpFcLGRmhwMftom0bsHvxE0bNBZW GLJf8xH4+atN7TvqNsXATuV1kNEFaGF2rDloUlDXQwDf3Q7LZB9I2+9AQ1mkHcN0PiIa tNew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757613709; x=1758218509; h=content-transfer-encoding:in-reply-to:content-language:from :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=dT+Q59Pc2L/rhFNESzM1Obx+v54bS+WG5xyH9LUjUpA=; b=WwxxbmCCLABcMZmRn9aA2ETS3UffspAxtKCpyOzuIV+SGVWOV8vs766QcuJk4kxM6e brhD04wnO9sHlplw5ZzY+Lcwmo7grxrxx1ippMr7mZtsGqWft/NkYbh8fvBJMmQ3KDUr RzCnQChDnxMX5/+Nt0p7545bW0lRi5dy/8/8/16OZB24C4Sh9he7JCWhAgHIaInW09of Tk7adM8fHuCKY81xyubXVaSsRdLjcSwYdx2qcf8K0SGDClPBdft6z+NtWO3rxGUAo+LA m+77dSROVm/QaE+I7psn4hpcHrcIKHryyVdGJ25MGxU1vuHbY3UwcKTcH/iTEzEJOmYH rh7A== X-Forwarded-Encrypted: i=1; AJvYcCXVbUXdg4+ZOQ6UyGdFzN3XIZPTHfiZJeSFADGVZ/OMhc9IetEEIjxT/MU+OaXIGAewe6dgg3imGC2G@nongnu.org X-Gm-Message-State: AOJu0Yy0FvQwKv/10qUilgKKxjVF2RysEraI4xOzlVMtOqOa9BR25eVC nHGUQY64ULU6OHdSv0YjHrYszijTxTQkpUqRXsN3ANmWLByM5rzS+jpaSvj+0UYpFrA= X-Gm-Gg: ASbGncvluyBg1siqZIzZ5kpBupVpXwqvClJoBjs4BwaFrG1ptsSVyaRRO+Ge4j2EuMY 6EvgfAkVlS3jVVjtcnEY9SoWmE7oq/+qFgdFZXDIBurbOqjt8BnXLFVzoB/60l22XEKPq8csMoJ kEjHw0ukqMvtBU54A9oXunR+88mVayoD2wejrVtpAhoYdFxHYq6sT8KN/gpq16hg5f01e/mEVMA 5j2y6erKq+ZUc52r6E6/7rtj/prV1umy5V3HUoiBXGL7XwRjE/KSFhN/tqeliYdo9vQqc9+uzHZ sOxzShNEj/B0qz18blIIW2J7rU/8lOAf7RzeOSG+pR4f9uNYLA4EHE4A+hmOtRbjCH/wWKoyTMW Iv83zU4FCtiSer/he5PTpla2WgYm1l7H8wul0YyctUDi+Vi1GYDXK6I5BVhAQcSzP/srxpsN0hF jZqvg= X-Google-Smtp-Source: AGHT+IFVpkQFWQnUNu1MWepE5aBvXL+kuTpzxhQw7lHHly64gf0mGgsUBkCDhq9gekN/sHbcKG/qVQ== X-Received: by 2002:a05:600c:468a:b0:458:be62:dcd3 with SMTP id 5b1f17b1804b1-45f211f2eb5mr3964795e9.17.1757613708455; Thu, 11 Sep 2025 11:01:48 -0700 (PDT) Received: from [172.16.30.12] (ipnet-92-225.static.simnet.is. [157.157.92.225]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45e037b9ebbsm34471925e9.11.2025.09.11.11.01.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 11 Sep 2025 11:01:48 -0700 (PDT) Message-ID: <0edf22b7-d2c6-4995-880a-03133d5043b6@linaro.org> Date: Thu, 11 Sep 2025 18:01:43 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 14/20] util: fix interleaving of error & trace output To: =?UTF-8?Q?Daniel_P=2E_Berrang=C3=A9?= , qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, Hanna Reitz , Kevin Wolf , =?UTF-8?Q?Marc-Andr=C3=A9_Lureau?= , Christian Schoenebeck , Manos Pitsidianakis , Stefan Weil , =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , Gerd Hoffmann , Paolo Bonzini , Markus Armbruster , "Dr. David Alan Gilbert" References: <20250910180357.320297-1-berrange@redhat.com> <20250910180357.320297-15-berrange@redhat.com> From: Richard Henderson Content-Language: en-US In-Reply-To: <20250910180357.320297-15-berrange@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::336; envelope-from=richard.henderson@linaro.org; helo=mail-wm1-x336.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 9/10/25 18:03, Daniel P. Berrangé wrote: > The monitor_cur_hmp() function will acquire/release mutex locks, which > will trigger trace probes, which can in turn trigger qemu_log() calls. > vreport() calls monitor_cur() multiple times through its execution > both directly and indirectly via error_vprintf(). > > The result is that the prefix information printed by vreport() gets > interleaved with qemu_log() output, when run outside the context of > an HMP command dispatcher. This can be seen with: > > $ qemu-system-x86_64 > -msg timestamp=on,guest-name=on > -display none > -object tls-creds-x509,id=f,dir=fish > -name fish > -d trace:qemu_mutex* > 2025-09-10T16:30:42.514374Z qemu_mutex_unlock released mutex 0x560b0339b4c0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) > 2025-09-10T16:30:42.514400Z qemu_mutex_lock waiting on mutex 0x560b033983e0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) > 2025-09-10T16:30:42.514402Z qemu_mutex_locked taken mutex 0x560b033983e0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) > 2025-09-10T16:30:42.514404Z qemu_mutex_unlock released mutex 0x560b033983e0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) > 2025-09-10T16:30:42.516716Z qemu_mutex_lock waiting on mutex 0x560b03398560 (../monitor/monitor.c:91) > 2025-09-10T16:30:42.516723Z qemu_mutex_locked taken mutex 0x560b03398560 (../monitor/monitor.c:91) > 2025-09-10T16:30:42.516726Z qemu_mutex_unlock released mutex 0x560b03398560 (../monitor/monitor.c:96) > 2025-09-10T16:30:42.516728Z qemu_mutex_lock waiting on mutex 0x560b03398560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842057Z qemu_mutex_locked taken mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842058Z qemu_mutex_unlock released mutex 0x564f5e401560 (../monitor/monitor.c:96) > 2025-09-10T16:31:04.842055Z 2025-09-10T16:31:04.842060Z qemu_mutex_lock waiting on mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842061Z qemu_mutex_locked taken mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842062Z qemu_mutex_unlock released mutex 0x564f5e401560 (../monitor/monitor.c:96) > 2025-09-10T16:31:04.842064Z qemu_mutex_lock waiting on mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842065Z qemu_mutex_locked taken mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842066Z qemu_mutex_unlock released mutex 0x564f5e401560 (../monitor/monitor.c:96) > fish 2025-09-10T16:31:04.842068Z qemu_mutex_lock waiting on mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842069Z qemu_mutex_locked taken mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842070Z qemu_mutex_unlock released mutex 0x564f5e401560 (../monitor/monitor.c:96) > 2025-09-10T16:31:04.842072Z qemu_mutex_lock waiting on mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842097Z qemu_mutex_locked taken mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842099Z qemu_mutex_unlock released mutex 0x564f5e401560 (../monitor/monitor.c:96) > qemu-system-x86_64:2025-09-10T16:31:04.842100Z qemu_mutex_lock waiting on mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842102Z qemu_mutex_locked taken mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842103Z qemu_mutex_unlock released mutex 0x564f5e401560 (../monitor/monitor.c:96) > 2025-09-10T16:31:04.842105Z qemu_mutex_lock waiting on mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842106Z qemu_mutex_locked taken mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842107Z qemu_mutex_unlock released mutex 0x564f5e401560 (../monitor/monitor.c:96) > Unable to access credentials fish/ca-cert.pem: No such file or directory2025-09-10T16:31:04.842109Z qemu_mutex_lock waiting on mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842110Z qemu_mutex_locked taken mutex 0x564f5e401560 (../monitor/monitor.c:91) > 2025-09-10T16:31:04.842111Z qemu_mutex_unlock released mutex 0x564f5e401560 (../monitor/monitor.c:96) > > To avoid this interleaving (as well as reduce the huge number of > mutex lock/unlock calls) we need to ensure that monitor_cur_hmp() is > only called once at the start of vreport(), and if no HMP is present, > no further monitor APIs can be called. > > This implies error_[v]printf() cannot be called from vreport(). > > Instead a decision about whether output will go to monitor_[v]printf() > or fprintf() must be made upfront, and then those functions called > directly. > > $ qemu-system-x86_64 > -msg timestamp=on,guest-name=on > -display none > -object tls-creds-x509,id=f,dir=fish > -name fish > -d trace:qemu_mutex* > 2025-09-10T16:31:22.701691Z qemu_mutex_unlock released mutex 0x5626fd3b84c0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) > 2025-09-10T16:31:22.701728Z qemu_mutex_lock waiting on mutex 0x5626fd3b53e0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) > 2025-09-10T16:31:22.701730Z qemu_mutex_locked taken mutex 0x5626fd3b53e0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) > 2025-09-10T16:31:22.701732Z qemu_mutex_unlock released mutex 0x5626fd3b53e0 (/var/home/berrange/src/virt/qemu/include/qemu/lockable.h:56) > 2025-09-10T16:31:22.703989Z qemu_mutex_lock waiting on mutex 0x5626fd3b5560 (../monitor/monitor.c:91) > 2025-09-10T16:31:22.703996Z qemu_mutex_locked taken mutex 0x5626fd3b5560 (../monitor/monitor.c:91) > 2025-09-10T16:31:22.703999Z qemu_mutex_unlock released mutex 0x5626fd3b5560 (../monitor/monitor.c:96) > 2025-09-10T16:31:22.704000Z fish qemu-system-x86_64: Unable to access credentials fish/ca-cert.pem: No such file or directory > > This change requires adding a stub for monitor_printf() since that > is now called directly by vreport(), where monitor_vprintf() was > only needed previously. > > Signed-off-by: Daniel P. Berrangé > --- > stubs/monitor-core.c | 5 +++ > tests/unit/test-util-sockets.c | 1 + > util/error-report.c | 60 ++++++++++++++++++++++++---------- > 3 files changed, 48 insertions(+), 18 deletions(-) Reviewed-by: Richard Henderson r~ > > diff --git a/stubs/monitor-core.c b/stubs/monitor-core.c > index 1e0b11ec29..70b1f7a994 100644 > --- a/stubs/monitor-core.c > +++ b/stubs/monitor-core.c > @@ -30,3 +30,8 @@ int monitor_vprintf(Monitor *mon, const char *fmt, va_list ap) > { > abort(); > } > + > +int monitor_printf(Monitor *mon, const char *fmt, ...) > +{ > + abort(); > +} > diff --git a/tests/unit/test-util-sockets.c b/tests/unit/test-util-sockets.c > index d40813c682..53733163dd 100644 > --- a/tests/unit/test-util-sockets.c > +++ b/tests/unit/test-util-sockets.c > @@ -76,6 +76,7 @@ Monitor *monitor_cur_hmp(void) { return cur_mon; } > bool monitor_cur_is_qmp(void) { return false; } > Monitor *monitor_set_cur(Coroutine *co, Monitor *mon) { abort(); } > int monitor_vprintf(Monitor *mon, const char *fmt, va_list ap) { abort(); } > +int monitor_printf(Monitor *mon, const char *fmt, ...) { abort(); } > > #ifndef _WIN32 > static void test_socket_fd_pass_name_good(void) > diff --git a/util/error-report.c b/util/error-report.c > index c0fcf388de..6c887047e3 100644 > --- a/util/error-report.c > +++ b/util/error-report.c > @@ -29,6 +29,9 @@ bool message_with_timestamp; > bool error_with_guestname; > const char *error_guest_name; > > +typedef void (*error_print_func)(void *opaque, const char *fmt, ...); > +typedef void (*error_print_vfunc)(void *opaque, const char *fmt, va_list ap); > + > /* > * Print to current monitor if we have one, else to stderr. > */ > @@ -151,34 +154,34 @@ void loc_set_file(const char *fname, int lno) > /* > * Print current location to current monitor if we have one, else to stderr. > */ > -static void print_loc(void) > +static void print_loc(bool cur, error_print_func print_func, void *print_opaque) > { > const char *sep = ""; > int i; > const char *const *argp; > > - if (!monitor_cur_hmp() && g_get_prgname()) { > - error_printf("%s:", g_get_prgname()); > + if (!cur && g_get_prgname()) { > + print_func(print_opaque, "%s:", g_get_prgname()); > sep = " "; > } > switch (cur_loc->kind) { > case LOC_CMDLINE: > argp = cur_loc->ptr; > for (i = 0; i < cur_loc->num; i++) { > - error_printf("%s%s", sep, argp[i]); > + print_func(print_opaque, "%s%s", sep, argp[i]); > sep = " "; > } > - error_printf(": "); > + print_func(print_opaque, ": "); > break; > case LOC_FILE: > - error_printf("%s:", (const char *)cur_loc->ptr); > + print_func(print_opaque, "%s:", (const char *)cur_loc->ptr); > if (cur_loc->num) { > - error_printf("%d:", cur_loc->num); > + print_func(print_opaque, "%d:", cur_loc->num); > } > - error_printf(" "); > + print_func(print_opaque, " "); > break; > default: > - error_printf("%s", sep); > + print_func(print_opaque, "%s", sep); > } > } > > @@ -199,34 +202,55 @@ real_time_iso8601(void) > G_GNUC_PRINTF(2, 0) > static void vreport(report_type type, const char *fmt, va_list ap) > { > + /* > + * Calling monitor_cur_hmp() will acquire/release mutexes, > + * which triggers trace probes, which can trigger > + * qemu_log calls, which would interleave with output > + * from this. Hence cache the monitor handle upfront > + * so any tracing appears before we start outputting. > + */ > + Monitor *cur = monitor_cur_hmp(); > + error_print_func print_func; > + error_print_vfunc print_vfunc; > + void *print_opaque; > gchar *timestr; > > - if (message_with_timestamp && !monitor_cur_hmp()) { > + if (cur) { > + print_func = (error_print_func)monitor_printf; > + print_vfunc = (error_print_vfunc)monitor_vprintf; > + print_opaque = cur; > + } else { > + print_func = (error_print_func)fprintf; > + print_vfunc = (error_print_vfunc)vfprintf; > + print_opaque = stderr; > + } > + > + if (message_with_timestamp && !cur) { > timestr = real_time_iso8601(); > - error_printf("%s ", timestr); > + print_func(print_opaque, "%s ", timestr); > g_free(timestr); > } > > /* Only prepend guest name if -msg guest-name and -name guest=... are set */ > - if (error_with_guestname && error_guest_name && !monitor_cur_hmp()) { > - error_printf("%s ", error_guest_name); > + if (error_with_guestname && error_guest_name && !cur) { > + print_func(print_opaque, "%s ", error_guest_name); > } > > - print_loc(); > + print_loc(!!cur, print_func, print_opaque); > > switch (type) { > case REPORT_TYPE_ERROR: > break; > case REPORT_TYPE_WARNING: > - error_printf("warning: "); > + print_func(print_opaque, "warning: "); > break; > case REPORT_TYPE_INFO: > - error_printf("info: "); > + print_func(print_opaque, "info: "); > break; > } > > - error_vprintf(fmt, ap); > - error_printf("\n"); > + print_vfunc(print_opaque, fmt, ap); > + print_func(print_opaque, "\n"); > } > > /*